1. 5.2 The Modern Periodic Table

2. 5.2 The Modern Periodic Table
A. How is the modern periodic table organized?
1. Mendeleev’s Periodic Table- arranged by order of increasing
atomic mass
2. Modern Periodic Table – arranged by order of increasing
atomic number.
Atomic number = number of protons = number of electrons

3. 5.2 The Modern Periodic Table
3. Periods
a. Row on the periodic table
b. As the atomic number increases, the number of energy levels filled increases, so more rows are filled in the periodic table.

4. 5.2 The Modern Periodic Table
4. Groups
a. Column in the periodic table.
b. Similar properties are found within groups.
1. Electron configurations are similar.
2. Chemical properties
are then similar.

5. 5.2 The Modern Periodic Table
5. Periodic Law- Pattern of repeating properties on the periodic table when the table is arranged by increasing atomic number.

6. 5.2 The Modern Periodic Table
B. What does the atomic mass of an element depend upon?
1. Distribution of the element’s isotopes in nature
a. Most elements are a mixture of 2 or mores isotopes.
b. Each isotope exists in differing amounts (%).
2. Masses of the element’s isotopes.

7. 5.2 The Modern Periodic Table
3. Scientists use carbon as the standard to determine the
mass of an element
a. An atom is so incredibly small, so using the unit of grams would not be useful.
b. Atomic mass unit (amu) is 1/12 of the mass of a carbon atom. .

8. 5.2 The Modern Periodic Table
C. What categories are used to classify elements on the periodic table?
1. Solids, Liquids and Gases

9. 5.2 The Modern Periodic Table
2. Elements that occur naturally and those that are man made.

10. 5.2 The Modern Periodic Table
3. Metals, Nonmetals or Metalloids

11. 5.2 The Modern Periodic Table
a. Properties of Metals
1). Good conductors of heat and electricity
2). Mostly solids at room temperature
3). Malleable- can be pounded in sheets
4). Ductile – can be drawn into wires
5). Shiny
6). Most abundant type of elements

12. 5.2 The Modern Periodic Table
b. Properties of nonmetals
1). Do not conduct heat and electricity
2). Insulators
3). Dull
4) Brittle
5). Low boiling points
6). Many are gases at room temperature
7). Some very reactive, other not reactive at all.

13. 5.2 The Modern Periodic Table
c. Properties of metalloids (also called semiconductors)
1). Ability to conduct heat and electricity varies with temperature
2). Found between metals and non metals on periodic table
3). Only 8: B, Si, Ge, AS, Sb, Te, Po, and At

14. 5.2 The Modern Periodic Table
D. How do properties vary across a period in the periodic table?
1. Across a period from left to right, the elements become less metallic and more nonmetallic in their properties.
2. The most reactive metals are on the left in Group 1, the most
reactive nonmetals are on the right in Group 17.

15. 5.2 The Modern Periodic Table
Review Questions:
1. What determines the atomic mass of an element?
the natural distribution of isotopes and the atomic numbers of those isotopes
the natural distribution of isotopes and the masses of those isotopes
the mass of the isotope of the element that has the most neutrons
the average number of protons in the element’s nucleus

16. 5.2 The Modern Periodic Table
2. Which of the following is not characteristic of metals?
ductile
good electrical conductor
typically solid at room temperature
Brittle

17. 5.2 The Modern Periodic Table
3. Within a period of the periodic table, how do the properties of the elements vary?
Metallic characteristics increase from left to right.
Metallic characteristics decrease from left to right.
Reactivity increases from left to right.
Reactivity decreases from left to right.

18. 5.2 The Modern Periodic Table
4. In the modern periodic table, elements are arranged in order of increasing atomic mass True False